Conventionally, various self light-emitting devices, which allow one or more luminous bodies to emit light using electric power generated by a photo-electric converting element, such as a solar battery, have been proposed. For example, in the publication of Japanese Laid-Open Patent Application Hei 9-49213, a road installation type signaling device equipped with a flat solar battery, multiple light emitting diodes arranged around the solar battery and a storage cell where electric power generated by the solar battery is accumulated is proposed. In this signaling device, the entire device is buried and installed in the road, and the electric power generated by the solar battery is accumulated in the storage cell during the day, and the light emitting diodes blink due to the electric power accumulated in the storage cell during the night.
In Japanese Laid-Open Patent Application Hei 8-199513, a light emitting indicator equipped with a flat solar battery, plural light emitting diodes, a storage cell and an electric circuit, and in which these constructional elements are buried into transparent epoxy resin, is proposed. Even in this light emitting indicator, the electric power generated by the solar battery is accumulated in the storage cell during the day, and the light emitting diodes blinks using the electric power during the night. Burying the construction elements into the epoxy resin results in improved weather resistance.
However, in the devices described in Japanese Laid-Open Patent Application Hei 9-49213 and Japanese Laid-Open Patent Application Hei 8-199513, since electric power is generated by a flat solar battery, high power electricity cannot be always generated during the day, but the high power electricity can be generated only for several hours when the sunlight enters almost vertically into the solar battery at a small angle of incidence. In other words, since the electric power required at night has to be accumulated during several hours, the light receiving area of the solar battery has to be large, with the problem that the device becomes excessively large.
When installing the devices described in Japanese Laid-Open Patent Application Hei 9-49213 and Japanese Laid-Open Patent Application Hei 8-199513 on a flat road, electric power can be accumulated in the storage cell. However, if the devices are installed on a slope, such as a slope formed on an inclined plane on the north side, since a great deal of sunlight is reflected on the surface of the solar battery, the desired electric power cannot be accumulated in the storage cell and the light emitting diodes cannot emit light during the night, making it difficult for drivers in vehicles traveling on the road to drive safely.
In recent years, a low cost, small and light weight self light-emitting device used for the purpose of safety at night by attaching it to a bicycle, a bag or a cap has been desired. When attaching these devices, a self light-emitting device is often installed close to a vertical state, and the electric power, which is supposed to accumulate in the storage cell cannot be generated because the sunlight enters almost parallel to the acceptance surface, making it impossible to practically use.
The objective of the present invention is to provide a self light-emitting device, where electric power to be generated is not affected by the installation location, and which can be manufactured at a low cost and is small and light weight.